Description
Problem Statement Server Code Server sample code Functionalities of your server loss is rare or even non-existent in typical campus networks, the server in this lab injects artificial loss to simulate the effects of network packet loss. The server creates a variable randomized integer which determines whether a particular incoming packet is lost or not. In the sample code, 30% of the client’s packets are simulated to be lost. You should study this sample code carefully, as it will help you write your Ping client. The server sits in an infinite loop listening for incoming UDP packets. When a packet comes in and if a randomized integer is greater than or equal to 4, the server simply capitalizes the encapsulated data and sends it back to the client; if the randomized integer is smaller than 3, the server needs to inform to the client which packet has been dropped and then client needs to retransmit the dropped packet. You need to develop your client code from scratch. The ping messages in this lab are formatted in a simple way. The client message is one line, consisting of ASCII characters in the following format: ping time_stamp where ping_index starts at 1 and progresses to 100 for each successive ping message sent by the client, and time_stamp is the time when the client sends the message. You client program should support the following: The client should send 100 pings to the server. Because UDP is an unreliable protocol, a packet sent from the client to the server may be lost in the network, or vice versa. Therefore, your client should support retransmitting the dropped packets. (Note that you client is not allowed to use socket timeout) Specifically, your client program should 1. send the ping message using UDP to the Ping server ; 2. print the ping response message from the Ping server if the ping message has not been dropped ; Client Code Ping Message Format Functionalities of your client 3. retransmit the same ping message if the previous ping message(s) have been dropped by the Ping server ; print which ping message needs to be retransmitted ; 4. calculate and print the round trip time (RTT) in seconds of each ping message/response pair. (Note that for the retransmitted ping request/response pairs, the starting time-stamp can be either the time-stamp of the initial ping request message or the most recent ping request message) 1. Start CSC361-VM , open a terminal, and type sudo mn -x to generate a simple network topology ; 2. Flush all arp caches (more details can be found in the provided WiresharkEthernetARP.pdf) ; 3. Run your Ping server over one of the hosts created (e.g., h1) python pingserver.py 4. Run your Ping client over one of the hosts created (e.g. h2) python pingclient.py You must demonstrate your working code inside the CSC361-VM using Wireshark. Using CSC361-VM , the server and the client must use different IP addresses and port numbers. Your Wireshark demo must capture all related packets, including ARP and UDP . You are required to create one single document before your demo that has The screen shot of all your ARP packets and at least 20 UDP packets The screen shot of your client You are also required to answer a few questions about your programming assignment during the demo in ECS 360. The evaluation scheme is: (50%) Correctness of Python code (20%) The created document before your demo. You should clearly write up how to handle Run the code Evaluation the retransmissions at both server and client sides and how to calculate the RTT for the retransmitted ping request/response pairs (30%) Questions and Answers during the demo (at least 5 questions) You will hand in the complete client/server code along with the single document created to Connex
